The micorflora of the oral cavity are able to live in their particular environment because they can adhere to oral surfaces instead of being swallowed. Several species of cariogenic streptococci are able to colonize and reproduce on tooth surfaces by attaching themselves to plaque or pellicle constituents. Streptococcus mutans has been shown to bind to dextrans or glucans which are synthesized by constitutive bacterial glucosyltransferase. Specific glucan receptors on the cell surface are responsible for glucan binding. One objective of this study is to investigate the roles of extracellular glucosyltransferases and their soluble and insoluble glucan products in the adherence process. It is likely that one of these substances adsorbs to enamel or pellicle-coated enamel and thereby initiates colonization when a S. mutans bacterial cell is bound. Another objective is to determine whether control of the glucan binding function through the action of antibody specific for the glucan receptor, is feasible. The procedures to be used to accomplish these goals include the use of adherence inhibition assay which will detect interference with any step in adherence, and an assay detecting the inhibition of dextran-induced agglutination which is specific for the glucan-binding step. Interference with adsorption and synthesis will be determined through the use of radio-labeled sucrose to observe changes in incorporation of C14 into glucan polymers. Specific pathogen free rats will be vaccinated with purified glucan receptors, placed on high sucrose diets, and challenged with cariogenic bacteria. Human oral secretions will be screened for activity in the dextran-induced agglutination inhibition assay. The results of these studies should contribute valuable information on caries pathogenesis and host-parasite relationships in caries infection.